• Analytical Science and Technology
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• v.36 no.6
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• pp.300-314
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• 2023

The quality of the products was investigated by analyzing fluorine content, pH, preservatives and tar colors in 31 dentifrice products (6 items for children) and 15 mouthwash products (2 items for children) marketed. It was intended to provide correct information to consumers by checking whether the standards and product indications match. As a result of measuring the fluoride concentration, 26 dentifrice and 15 mouthwash products contained from 48 to 1,472 ppm and from 85 to 225 ppm, respectively. Fluorine detection rates of dentifrice and mouthwash products were 83.9 and 83.3 %, respectively showing similar levels. Of the 41 fluoride-detected dentifrice and mouthwash products, 40 were 90.7~109.8 % of the displayed amount and suitable for the fluorine content standard of 90.0 to 110.0 %, but one dentifrice was found to be inappropriate at 36.3 % of the content indicated on the product. The pH of the dentifrice was 5.1~9.4, and the mouthwash was 4.2~6.2, which met all standards. As a result of simultaneous analysis of the concentration of six preservatives, benzoic acid was detected the most in 15 cases with a 30.6 % detection rate, sorbic acid was detected in 9 cases (detection rate of 18.4 %), and all four types of methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-hydroxybenzoate were not detected. As a result of analyzing the concentration of 10 types of tar colors, six types including red40, yellow4, yellow5, yellow203, green3, and blue1 were detected in a total of 9 cases (2 dentifrices and 7 mouthwashes) with blue1 being the most frequently detected. Detected fluorine concentration, added preservatives and tar colors were consistent with the product markings and it was well written on product packaging. The detected preservatives and tar colors were at a safe level due to low risk compared to Acceptable Daily Intake.

• Journal of Food Hygiene and Safety
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• v.33 no.1
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• pp.83-88
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• 2018

The purpose of this study was to investigate and evaluate the safety of the wet tissues. In this study, we analyzed sterilizing preservatives and the presence of harmful substances in 62 wet tissue samples in the market. The contents of preservatives, formaldehyde and methanol were analyzed by HPLC and headspace-GC, respectively. Cetylpyridinium chloride was detected as 7-13 ppm in 5 samples. Sodium benzoate was detected in 46 samples ranging from 200 ppm to 3500 ppm, and 9 ppm of methylparahydroxy benzoate was detected in 1 sample. Propylparahydroxy benzoate was not detected in any samples. 5 ppm of methylchloroisothiazolinone and 140 ppm of methylisothiazolinone were detected in 1 sample. Formaldehyde was detected as $0.0069-1.796{\mu}g/g$ in 59 samples. Methanol was detected ranging from 2 ppm to 51 ppm in 22 samples, and 4 samples showed more than 20 ppm of the legal limit. The pH of the wet tissues was 4.0 to 8.2. Continuous investigation and monitoring are necessary to ensure safe distribution of products.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.4
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• pp.613-618
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• 1995

This study was carried out to investigate the effect of extracting pH on the components and color of seasame protein concentrate(SPC). The protein contents of SPC by extracted at pH 2.0, 7.0, 9.0 and 11.0 were 60.57, 67.72, 79.50 and 83.44%, respectively. Most of the phytates were removed in SPC extracted at pH 7.0, 9.0 and 11.0, but the phytate content of SPC extracted at pH 2.0 was about the same as that of defatted sesame flour. The highest decrease of phytate was found in SPC extracted at pH 11.0(94.80%). SPC extracted at pH 2.0 contained the highest amount of Ca, Mg, Fe and Zn than those in other SPC prepared, while highest amount of Cu was found in SPC extracted at pH 11.0. Sodium content was similar among all the SPC prepared. SPC extracted at pH 7.0 resulted in brighter clor, but SPC extracted at pH 11.0 showed a little darker in appearance.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.242-242
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• 2010

SiO2박막을 이온 감지막으로 이용한 pH농도센서를 제작하였다. 현재 많은 연구중인 pH센서, pH-ISFET(pH-Ion Sensitive Field Effect Transistor)는 용액과 기준전극간의 전기화학적 변위차를 이용하여 pH를 센싱한다. pH-ISFET는 기존 CMOS공정을 그대로 이용할 수 있고, 이온감지막의 변화만으로 다양한 센서를 제작할 수 있어 최근 많은 연구가 진행 중이다. 하지만 FET를 제작하기 위한 공정의 복잡성과 용액의 전위를 정해주고 FET에 바이어스를 인가해줄 기준전극이 반드시 필요하다는 제한성이 있다. 따라서 본 연구에서는 SOI 기판을 이용하여 간단한 구조의 pH센서를 제작하였다. 센서는 (100)결정면을 가지는 p-타입 SOI(Silicon On Insulator)기판을 사용하였으며 포토리소그래피 공정을 이용하여 back-gated MOSFET구조로 제작하였다. 이온감지막으로 사용할 SiO2박막은 RF 스퍼터링을 이용하여 $100{\AA}$ 증착하였다. 바이어스는 기존 pH-ISFET와는 다르게 기준전극 대신 기판을 backgate로 사용하여 FET에 바이어스를 인가해 주었다. pH 용액 주입을 위해 PDMS재질의 챔버를 제작하고 실리콘글루를 이용하여 센서에 부착하였다. pH12부터 pH4까지 단계적으로 누적시키며 챔버에 주입하였고, pH에 따른 드레인전류의 변화를 관찰하였다. pH용액을 챔버에 주입시, pH농도에 따라 제작된 센서의 문턱전압이 오른쪽으로 이동하는 결과를 관찰할 수 있었다. 결과적으로, 구조가 간단한 pseudo MOSFET을 이용하여 pH센서의 적용가능성을 확인하였으며 SiO2박막 역시 본 pH센서의 이온감지막의 역할과 센서의 안정성을 향상시킬 수 있다는 점을 확인하였다.

• Economic and Environmental Geology
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• v.43 no.4
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• pp.315-332
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• 2010

All of the water and stone-dust samples with or without flocculant, in and around quarry mines, were analyzed for total concentrations of heavy metals, cyanide(CN), toxic organic compounds and organic phosphorus. Extraction experiments on stone-dust by EDTA and various pH solutions were also carried out, in order to evaluate the contaminant leaching from the long-term heaped stone-dust within quarry mines. The concentrations of $Cr^{6+}$, Hg, CN, TCE/PCE and total phosphorus in all samples (water and stone-dust) were under detection limits, confirming no environmental contamination from stone-dust in quarry mine areas. Lead and cadmium were not detected in all water samples. Copper and zinc were found in some water samples, and arsenic was detected in a few water samples. But they also showed levels much lower than the drinking water standard. Results of the extraction experiments by EDTA and pH solutions showed that Pb, Cr, Cd, Cu and Zn were leached out in less amounts or under detection limits. Arsenic was detected only at pH 3. From above results, we suggested that environmental contamination by quarry mine development is likely to be minor or negligible.

• Korean Journal of Food Science and Technology
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• v.36 no.2
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• pp.355-360
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• 2004

Residual contamination levels of natural microflora in strawberries were evaluated. Approximate counts of total aerobic mesophilic bacteria, total coliforms, and lactic acid bacteria were 8, 2, and 3 log CFU/g, respectively, whereas those of Escherichia coli and yeasts/molds were under the detection limit (<10 cells/g). Growth inhibition degrees of total aerobic mesophilic bacteria, total coliforms, and lactic acid bacteria were also evaluated based on three hurdles of preservative, storage temperature, and pH of strawberry paste prepared as model system. Strawberry paste was stored at low ($4^{\circ}C$), room ($20^{\circ}C$), and high ($37^{\circ}C$) temperatures. Potassium sorbate was added as a preservative up to 0.1%. Acidity of strawberry paste was adjusted to pH 4 or 7. During 7-day storage, inhibitory effects of the hurdles against bacterial groups were: storage temperature > pH of strawberry paste > addition of potassium sorbate. Combination of three hurdles most effectively inhibited growth of residual microflora.

• Clean Technology
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• v.8 no.4
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• pp.199-203
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• 2002

To investigate the optimal conditions for biodegradation of toluene by Pseudomonas fluorescens KCTC 1767 in a batch soil-bioreactor, the effects of rpm change from 60 to 180, and temperature change from $15^{\circ}C$ to $30^{\circ}C$ in a batch culture and the flow rate change from 55 mL/min to 85 mL/Min in soil-bioreactor on the biodegradation of toluene were studied. In a batch culture the optimal operating conditons were 60 rpm, and $30^{\circ}C$ at initial pH 7, In a soil-bioreactor the optimal flow rate was 55 mL/min in the flow rate of circulation. The lower flow rate of circulation may help to biodegrade toluene adsorped in soil and dissolved in underground water.

• Journal of Animal Environmental Science
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• v.12 no.1
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• pp.7-12
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• 2006

Ammonia emission from swine production process originates from three major sources: manure storage facility, swine housing, and land application of manure. Most of the ammonia gas that are emitted from swine production operations is the by-product of aerobic or anaerobic decomposition of swine waste by microorganism. Knowing the ammonia emission rate is necessary to understand how management practices or alternative manure handling process could reduce impacts of this emission on the environment and neighbors. Ammonia gas emission from pig slurry is very difficult to predict because it is affected by many factors including wind speed of slurry surface, temperature or pH of the swine slurry, sort breed differences and classes, and diets. This study was carried out to effects of pH and temperature on ammonia gas emission from growing-finishing pig slurry. Treated far slurry in this study were pH and temperature. Results showed that pH of slurry variable changes 5, 6, 7, 8 upon an addition of NaOH and $HNO_3$, respectively. The temperature of the slurry which was contained in a water bath maintained at increasing levels ranging from 10 to $35^{\circ}C$. Ammonia emission rate of influenced pH and temperature such that the increase in pH or temperature resulted to an increase in ammonia emission. The ammonia gas was not detected at pH 5 and 6. Moreover, at a slurry of pH 8, the ammonia ranged from 28 to 60ppm and 8-29 ppm at slurry pH of 7 while temperature was 13 to $33^{\circ}C$. When slurry pH was>6, the ammonia emission was significantly increased according to rise in temperature in contrast to acid treatment of the pH. There was also a significantly increase in ammonia emission relative to slurry pH of 7 to 8. The above findings showed that to effectively reduce ammonia emission from slurry of growing-finishing pigs, the pH and temperature should be maintained a low levels.

• Korean Journal of Environmental Agriculture
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• v.26 no.3
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• pp.254-258
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• 2007

Several physicochemical properties including water solubility, vapor pressure, and hydrolysis of bistrifluron benzoylphenylurea insecticide developed in Korea, were measured based on OECD guidelines for testing of chemicals and Toxic Substances Control Act Test guidelines. Water solubility was low showing 30 ${\mu}g/l$ at $25^{\circ}C$ and in hydrolysis study, half-life at $20^{\circ}C$ was 10.9 days (pH 9.0) and was stable in pH 7.0 solution. At $40^{\circ}C$ hydrolysis rate was 20.6 days (pH 7.0) and 1.5 days (pH 9.0). The vapor pressure of bistrifluron was not obtained from vapor pressure experiments at $25^{\circ}C$ because the bistrifluron was not detected. Therefore, the vapor pressure was determined to be ${\leq}\;2.05{\times}10^{-8}$ torr which was calculated to apply the detection limit (50 ng) of bistrifluron. And this value is suggests it would not give environmental contamination by volatilization.

• KSBB Journal
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• v.24 no.1
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• pp.106-112
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• 2009

An optical sensing membrane has been fabricated to measure the concentration of dissolved oxygen(DO) and pH value simultaneously. It has employed HPTS as a pH sensitive dye and a ruthenium(II) complex as a DO sensitive dye. The sensing membrane has been applied to wells in a 24-well microtiter plate. Using the 24-well microtiter plate the concentrations of dissolved oxygen and pH values have been on-line monitored during the cultivations of E.coli DH5${\alpha}$, B.cereus 318 and P.pastoris X-33. On-line monitoring of DO and pH in microorganism cultivation processes showed good performance of the sensing membrane containing 5 mM HPTS and 2 or 5 mg/mL Rudpp.